Yeah swirl flaps, sorry, late night posting does strange things to the link from head to keyboard!
That's a heck of a lot of cash! For what's in an adapter it's difficult for me to see nearly $10k AUD value, perhaps the BMW box is the go.... Or perhaps I can have something made locally.
From what I've found chatting to the local dealership, internally the M57 variants are identical, so the power differences come from head differences, mapping, and the number of turbos you hang off the side. I'd like to set myself a target of 200Kw and 600Nm which I'm sure is achievable...